Process for manufacturing shot



pr 1938- J. M. OLlN ET AL 2,113,280

PROCESS FOR MANUFACTURING SHOT Filed May 23, 1953 lNVENTOR J /W? M 07/77 P/7///,'0 /l. 501/777 B Y M b (UM/0, (g urk ATTORNEYS Patented Apr. 5, 1938 PATENT bFFlCE 2,113,280 PROCESS FOR MANUFAUIURING SHOT John M. Olin,

Conn,

corporation of Alton, 111., and Philip assignors to Winchester Repeating Arms Company, Maryland A. Smith,

New Haven, Gonm, a

Application May 23, 1933, Serial No. 672,395

4 Claims.

This inventiomrelates to shot and more particularly to shot formed of zinc or zinc alloys.

Heretofore there has been no known method of producing commercial zinc shot of the sizes 5 ordinarily used in shot gun cartridges. In our copending application Serial No. 672,394 filed May 23, 1933 we have disclosed and claimed of making shot wherein the globules or particles While our copending application is directed to the use of this process in connection with any desired metal and specifically to the use of the process in connection with scrap lead, it may also not substantially higher than the 20 carded in the present practice shot.

In carrying out our invention we employ apparatus substantially similar to that now used in the manufacture of lead shot wherein a perforat- 25 ed drip pan is provided at the top of the shot tower and the molten metal is fed into the drip pan and allowed to pass into the top of the tower through the openings in the pan. In the usual practice of making lead shot wherein'commer- 30 cially pure lead is employed in combination with of making lead assume a spherical shape but are tear-shaped or have small tails or whiskers. We have found 40 that spherical pellets of zinc may be obtained by maintaining a reducing or inert atmosphere in the tower, or at least in the upper portion of the tower where the particles or globules first assume a spherical shape. Any suitable reducing or in- 45 ert gas may be employed for this purpose. As

hydrogen or any equivalents of these materials.

As an inert medium through which the particles i of zinc may pass we may employ nitrogen.

Where a reducing gas is employed it is necessary to take precaution not to develop an explosive mixture in the shot tower.

In the accompanying drawing we have illustrated a shot gun cartridge forming a part of percentage disthis invention and have also illustrated apparatus for carrying out shot. In the drawing:

The figure is a diagrammatic view, in section, of the upper portion of a shot tower provided with means for maintaining the desired conditions in the shot tower.

As stated, the process described in our copending application, Serial No. 672,394 may be employed in the manufacture of the zinc shot and the application of such process to the manufacture of such shot is claimed the drawing the apparatus disclosed therein consistsof the upper portion of a conventional shot tower with means for supplying the inert or reducing'gas to the towe The floor Ill at the top of the tower is provided with an opening into which a skeleton frame ll loosely fits. This frame forms a support for the drip pan or colander l2 and also supports the upper end of cylinder I 3. An inlet pipe I 4 opens into the cylinder cylinder l3 and maintain ing atmosphere at the perforations in the drip pan. The cylinder I3 is of the usual construction and its length is ordinarily dependent on the size of the holes in the drip pan and the average size of the pellets desired in that particular run of the shot tower. In carrying out the process, zinc or a zinc alloy is fed to the drip pan in molten condition, preferably syphoned from a large fusion kettle (not shown), through a feed pipe IS in accordance with the usual practice. The metal drips through the perforations in the bottom of the pan and immediately comes in contact with the atmosphere of reducing gas or inert gas. Under such conditions we have found that the globules or particles of zinc coming from the bottom of the drip pan will assume a spherical form. During the operation of the tower it is advantageous to prevent the danger of explosion by burning the gas at'the bottom of the cylinder as indicated at It. The pellets or shot formed descend through the cylinder and the globules congeal sufliciently to prevent deformation when they strike the water at the bottom of the tower. The pellets fall into a water bath 20 as is the usual practice in the manufacture of shot and are cooled. They are removed, from the water tank, dried and sorted to remove imperfectly shaped pellets in the usual manner.

While we are unable to offer a sound scientific explanation of the reason why spherical pellets the process of producing zinc herein. Referring to g oi! zinc may be obtained when a reducing gas or an inert gas is maintained in the cylinder instead of air, we believe that the true explanation centers around certain obscure principles of the laws of surface tension as applied to a molten metal body falling freely. Whatever may be the true explanation or these principles there is the net commercial result that we are able to iorm zinc pellets in substantially the same manner that has heretofore been employed in the manufeature of lead shot. As stated above, this permits us to employ zinc shot either alone or in admixture with lead shot or other metal shot in the manufacture of shotgun cartridges and to obtain ballistic characteristics for cartridges of various calibers that have'heretoiore been impossible.

The zinc shot so obtained is spherical in shape according to the usual shot making practice and the percentage oi! pellets discarded because of irregular shape is not substantially higher than the percentage discarded in the present practice of making lead shot. ployed in the process and rial may be, therefore, reduced low those now prevailing in ordinary ing.

While we have disclosed the invention in connection with the conventional type of shot gun cartridge employing a paper tube, it will, or course, be apparent that the invention can be employed in connection with shot shells of the Scrap zinc may be cmthe cost of raw mateconsiderably beshot makty-pe now made in which a brass cartridge case is employed in place of the paper type. a

We claim:

1. The process of making substantially spherical shot suitable for use in the manufacture of shot gun cartridges which comprises separating molten zinc into globules at the top of a shot tower, and protecting said zinc globules from contact with oxygen during at least the initial part of their flight down said shot tower, whereby said globules are caused to assume a substantially spherical shape during the initial part of their flight.

2. The process of making substantially spherical shot suitable for use in the manufacture of shot gun cartridges which comprises separating molten zinc into globules at the top of a shot tower and maintaining an atmosphere of reducing gas in a portion of the tower through which the fused zinc globules start their flight, whereby said globules are caused to assume a substantially spherical shape during the initial part of their flight.

3. The process 01 making substantially spherical shot suitable for use in the manufacture of shot gun cartridges which comprises introducing molten zinc into a perforated drip pan at the top of a shot tower, permitting the molten zinc to flow through the perforations into the top of the shot tower, and protecting said molten zinc from contact with oxygen during at least the initial part of its flight down said shot tower, whereby said globules are caused to assume a substantially spherical shape during the initial part of their flight.

4. In the process of making substantially spherical shot for use in the manufacture of shot gun cartridges from zinc, the step which comprises protecting the zinc globules from contact with oxygen during at least the initial portion of their flight down a shot tower.

JOHN M. OLIN. PHILIP A. SMITH. 

